3. Put a (?) the box that most precisely describes the language.
Rec. R.E. non-RE
ADFA
AREX
coACFG
EQDFA
ATM
EQTM
coEQTM
coHALTTM
coATM
REGULARTM
The languages are,
ACFG = \{ (G, w) | G is a CFG that generates string w \}
ADFA = \{ (B, w) | B is a DFA that accepts input string w \}
AREX = \{ (R, w) | R is a regular expression that generates string w \}
ATM = \{ (M, w) | M is a TM and M accepts w \}
EQDFA = \{ (A, B) | A and B are DFAs and L(A) = L(B) \}
EQTM = \{ (M1, M2) | M1, M2 are TMs and L(M1) = L(M2) \}
HALTTM = \{ (M, w) | M is a TM and M halts on input w \}
REGULARTM = \{ (M) | M is a TM and L(M) is a regular language \}
For a language X the language coX is the language of the complement
set of X.
